Thread severing structure for sewing machines



Dec, 29, 1959 v. M. GINWRIGHT 2,918,887

THREAD SEVERING STRUCTURE FOR SEWING MACHINES Filed Jan. 7, 1958 4Sheets-Sheet 1 E! v 7 Z! I I l I MN TIE- Z1 V/l/IA INVENTOR:

Dec. 29, 1959 v. M. GINWRIG HT 2,918,887

THREAD SEVERING STRUCTURE FOR SEWING MACHINES Fil ed Jan. 7, 1958 4Sheets-Sheet 2.

INVENTOR:

Dec. 29, 1959 v. M. GINWRIGHT 2,918,887

THREAD SEVERING STRUCTURE FOR SEWING MACHINES Filed Jan. 7, 1958 4Sheets-Sheet 5 INVENTOR:

Dec. 29, 1959 v. M. GINWRIGHT ,8

THREAD SEVERING STRUCTURE FOR SEWING MACHINES Filed Jan. 7, 1958 4Sheets-Sheet 4 FlE- E INVENTOR:

r 2,918,887 IC A Patented Dec. 29, 1959 THREAD SEVERING STRUCTURE FORSEWING MACHINES Victor M. Ginwright, Jackson, Ala., assignor to VanityFair Mills, Inc., a corporation of Pennsylvania Application January 7,1958, Serial No. 707,541

6 Claims. (Cl. 112-252) This invention concerns a unique automaticthread severing structure for sewing machines and the like, whichstructure is adapted to sever the sewing thread close to the Work pieceat the completion of an edge seaming or thread applying operationperformed by the machine.

The automatic thread severing means heretofore avail able for sewingmachines, comprise special elements and parts, as well as structural andfunctional characteristics that make such prior art means more or lesscostly, complicated and otherwise unsatisfactory from a practical,commercial, or operational standpoint.

One object of my invention is to provide a novel automatic threadsevering structure for sewing machines and the like, which substantiallyovercomes the indicated and other detrimental and undesirable featuresand characteristics of the similar prior art automatic thread severingmeans.

Another object is to provide such a structure in which simplicity ofdesign, construction and operation are achieved to a substantiallymaximum extent.

An additional object is to provide such a structure which can beproduced by simply modifying the standard or conventional presser footof a sewing machine, so that a certain portion thereof cooperates in anew thread severing manner with one of the teeth of the feed dog elementof the machine, after completion of the thread applying operation to thework piece acted on by the machine.

It is also an object to provide such a structure which includes a newpresser foot having a flat case hardened bottom surface portion that isinterrupted by a space area defined by a special wall formation arrangedto effect a cutting edge in crosswise overextending relation to thesewing thread that normally contactingly travels along said bottomsurface portion directly above the teeth of the feed dog element of themachine.

Another object is to provide a new presser foot of the type indicated inwhich the said special cutting edge including wall formation is effectedby the provision ofan aperture, slot, recess, cavity, or the like, thatis arranged to extend upwardly from a bottom surface portion of thepresser foot, so that the cutting edge is formed at the juncture area ofsaid wall formation and bottom surface portion.

Another feature of the invention resides in the provision of a newpresser foot of the type indicated which can be readily substituted forthe standard, or conventional type presser foot of certain sewingmachines, in such manner as to effect automatic severance of the sewingthread at the completion of an edge seaming or thread applying operationperformed by the machine.

Another object is to provide a new presser foot of the type indicatedwhich comprises a flat bottom surface portion along which contactinglytravels the applied thread of the work piece acted on by the machine,and a presser foot bottom surface portion interrupting wall formationarranged to effect a cutting edge in crosswise overextending relation tosaid thread at a certain location in its path of travel along saidbottom surface portion.

Another object is to provide a novel automatic thread severing structurefor sewing machines and the like having a stationary needle plateprovided with a chaining finger and a reciprocably operable work feeddog member arranged in spaced axially aligned relation forwardly of saidchaining finger, which comprises the combination with the foregoingelements, of a vertically movable presser foot having a fiat bottomsurface portion adapted to be placed in contacting relation on the workpiece area to which the thread is applied by the machine and which isacted on by said feed dog member, a wall formation on said presser footwhich in configuration may be circular, straight, etc., and arranged soas to provide an interrupting space area in said bottom surface portionabove the feed dog member, and a cutting edge on said wall formationarranged in juncture forming relation with said bottom surface portion.

With these and other objects in view, which will be come more apparentfro-m the following detailed description of the practical andillustrative embodiments of my novel developments shown in theaccompanying drawings, the invention comprises the new automatic threadsevering structure for sewing machines and the like, the elements,features of constnlction and arrangement of parts in cooperativerelationship, as more particularly indicated and defined by the heretoappended claims.

In the drawings:

Figure 1 is an enlarged top plan view of one form of foot shoe, orpresser foot element for seamertype sewing machines, that forms part ofmy invention.

Fig. 2 is a side elevational view of the presser foot element shown inFig. 1, as it appears when attached to the usual or standard operatingarm of a certain seamer type sewing machine.

Fig. 3 is an enlarged elevational sectional view, taken substantially asindicated by the arrows 3--3 in Fig; 1.

Fig. 4 is an enlarged top plan view of a standard needle plate for acertain seamer type sewing machine, with a conventional sewing machineneedle indicated in cross section at its usual point of operation andthe presser foot element of Fig. l partly indicated in superimposedrelation by dot-and-dash lines to show its proper positional andoperational location in relation to said usual sewing machine parts.

Fig. 5 is a view similar to Fig. 4, but with the presser foot element ofFig. 1 shown in full lines and a fabric work piece having an edge seamapplied thereto between the presser foot element and needle hole piece,as during the operation of the sewing machine.

Fig. 6 is an enlarged elevational sectional view taken substantially asindicated by the arrow 66 on Fig. 5.

Fig. 7 is a view similar to Fig. 6, but showing the fabric work pieceand feed dog element in an advanced position.

Fig. 8 is a view similar to Figs. 6 and 7, but showing the fabric workpiece advanced beyond the feed dog element and the seam thread formationschematically indicated in trailing relation.

Fig. 9 is a view similar to Figs. 6, 7, 8 and 9, but with the partsshown when automatic severance takes place of the trailing seam threadformation.

Fig. 10 is a top plan view of Fig. 9, and

Fig. 11 is a partial view of the presser foo-t element, as depicted inFig. 1, showing a modified feature of the invention.

For purposes of practical illustration, or exemplification, the presentinvention is herein disclosed as applied to, or embodied in, a sewingmachine known as a Superlock machine, which is made and sold by Wilcox &Gibbs Sewing Machine Co., Ltd. of London, England. However, only thosewell known parts of such a standard or conventional sewing machine areshown in the drawings as are deemed necessary to make clear theconstruction and operation of my invention. For more detailedinformation COncerning the parts, construction and operation of saidSuperlock sewing machine, reference may be had to the literature,publications and patents publicly available relative thereto and moreparticularly to the booklet entitled Instruction Book and Parts Listmade available by the Wilcox & Gibbs Sewing Machine Co. and copyrightedby the latter in 1940. From this practical exemplification of myinvention, it will be readily apparent to those skilled in this art howthe invention can be embodied in, or applied to, other types of sewingmachines, in the same or in a similar manner, for the purpose ofaccomplishing substantially corresponding purposes, advantages andresults.

It Will facilitate an understanding of my invention to first identifythose usual and well known parts disclosed in the drawings whichconstitute certain standard elements and means of the said Superlocksewing machine. In this connection it is, of course, to be understoodthat all the other parts which make said machine complete and operative,but which are not disclosed in the drawings, are assumed to be presentto perform their usual functions in cooperative relation with the partsshown and likewise, in relation with the disclosed form of my invention,so that the latter will be effective in its intended purpose ofautomatically severing the sewing thread after the machine has completedits sewing, or thread applying operation, on a fabric work piece.

Assuming that such a Superlock sewing machine is set up to apply a chainstitch formation along two combinedly aligned fabric edges that arearranged in superimposed relation with each other so that the saidstitch formation will effect a seam, or juncture, at this location ofthe fabric work piece acted on by the machine, then certain of thestandard Superlock machine parts shown in Fig. 4 will come into play,such as a needle plate 1 which is provided with a chaining finger 2, aneedle 3, and a feed dog 4 having integrally combined therewith anauxiliary feed dog element 5. By referring to Fig. 5, it will beapparent how a two-ply fabric work piece, schematically indicated by theletter F, is positioned relative to the sewing machine parts shown inFig. 4, and moves in the direction of the arrow in Fig. 5, to effectapplication of the chain stitch formation, or edge seam schematicallyindicated at 6, that priginates at the chaining finger 2 by cooperativemovement of the needle 3 and the primary and secondary looper elementsand mechanisms, not shown. Also active in this standard arrangement ofthe Superlock sewing machine is a conventional foot shoe, or presserfoot element E, which is made of steel and is similar to, but notexactly like that shown in Fig. 5. One of the functions normallyperformed by the element E is to yieldingly press the fabric F againstthe feed dog elements 4 and 5 during the said edge seam applyingoperation.

However, the foot shoe, or presser foot element E shown in Fig. 5,differs from a standard type foot shoe of the said Superlock sewingmachine in that it embodies two important structural changes. That is tosay, it is provided with (l) a vertically extending circular aperture A,and (2) the metallic wall area surrounding said aperture, particularlywhere the wall formation of the aperture is in juncture forming relationwith the bottom surface of the element E, is subjected to a casehardening process, so that a sharp and hardened cutting edge is providedat least at the front juncture forming edge section of said wallformation and bottom surface.

The inclusion of the said two new structural features in the foot shoe,or presser foot element E, is consequently carried out in accordancewith my invention.

Otherwise, the foot shoe E in design, structure and size correspondsexactly with the standard foot shoe of the Superlock sewing machine andwhich standard foot shoe is utilized in cooperative combination with theother elements of the Superlock machine for the purpose of applying achain stitch formation, or juncture seam, to a fabric work piece, aspreviously explained. It is noted that the said standard foot shoe ofthe Superlock machine is identified as part 182,015 in the previouslyreferred to Instruction Book and Parts List published and distributed bythe Wilcox & Gibbs Sewing Machine Co.

The new foot shoe E is shown in Figs. 1, 2 and 3 of the drawings andwill next be more particularly described. The foot shoe E of myinvention is preferably formed of steel, the same as the said Superlockfoot shoe, and after the hole or aperture A has been provided therein,it is subjected to the case hardening process, as explained. The footshoe E generally comprises a front section 8, a rear section 7, anintermediate section provided with an indentational space 9 into whichextends an integral chaining finger or element 10, adjacently to whichthe needle of the sewing machine is normally vertically reciprocated, aswill be apparent from Fig. 4 in which the foot shoe E is partlydisclosed in dot-and-dash lines when arranged in its superimposedcooperative relation with the needle plate l and the feed dog elements 4and 5. The upwardly inclined portion of the front foot shoe section 8 isprovided with a threaded aperture 11, as usual, in which is seated amachine screw 12 arranged to fixedly secure the foot shoe E to astandard foot hinge spring 13 of the usual vertically movable foot shoeoperating arm structure 14 of the Superlock sewing machine. Thestructure 114 is arranged to facilitate vertical movement of the footshoe E by a control element, not shown, so that the bottom fiat surfaceof the foot shoe E can be brought, at will, into yielding pressureexerting contact with the top surface of the fabric work piece, directlyabove the feed dog elements 4 and 5, as indicated in Fig. 4 and as wellknown.

The vertically extending circular aperture A is so located in the rearsection 7 of the foot shoe E, that the center point thereof lies in thelongitudinal axial line of the chaining finger 2 of the needle plate 1!.and the similar element 10 of the foot shoe E. The usual sharp upperedge of the hardened steel front tooth of the auxiliary feed dog 5 is indiametrical alignment with the aperture A when the said feed dog element5 is in its rearward position. By referring to Figs. 5 and 6 it will benoted that, in accordance with this arrangement of the aperture A, theseam 6 of the fabric work piece F will be constantly maintained in linewith the aperture A and between the teeth of the auxiliary feed dogelement 5 and the flat bottom surface of the rear section 7 of the footshoe E, when the said teeth are raised during the forward or feedingmovement of the work piece F. At the starting, or initial position, ofthe auxiliary feed dog element 5, the sharp upper edge of the fronttooth of the latter is in diametrical alignment with the aperture A, asclearly shown in Figs. 4, 5 and 6. When the auxiliary feed dog element 5has completed a single work piece advancing forward step or movement, asusual, its position in relation to the aperture A will be as shown inFig. 7.

Fig. 8 shows the position of the work piece F after the rear edgethereof has advanced or has passed immediately beyond the teeth of theauxiliary feed dog element 5. At this point in the operation of thesewing machine, the seam formation or tail T that is formed only by thesewing thread, idly trails in a straight line behind the seam 6 that hasbeen applied to the fabric work piece F, at a location between thebottom surface of the foot shoe section 7 that includes the surfaceinterrupting space area, or zone, established by the wall structure thatdefines the aperture A, and the teeth of the auxiliary feed dog element5. It will be noted that the diameter of the aperture A is such, thatthe semi-circular rear section of the wall formation that establishesthe presser foot bottom surface portion interrupting space area, orzone, is arranged to effect a cutting edge in crosswise overextendingrelation to the sewing thread, or seam 6, at a certain point in itstravel along said bottom presser foot surface portion.

Immediately after the fabric work piece F passes beyond the rear end 7of the bottom surface of the presser foot E, as shown in Fig. 9, thesaid presser foot drops slightly and the bottom surface thereof thencomes into contacting relation with the top edges of the teeth of thefeed dog 4 and the teeth of the auxiliary feed dog element 5, duringthat portion of the feed dog operating cycle where the teeth thereof arein raised position. This will cause the portion of the seam tail T, thatis of reduced width in relation to the seam 6 and lies above the teethof the auxiliary feed dog element 5, to be moved upwardly into theaperture A. A shearing or severing action is then exerted on the bentportion of the seam tail T located between the sharp semi-circular edgeformed at the juncture of the rear wall portion that partly defines theaperture A and the bottom surface of the foot shoe section 7, and thesharp upper edge of the first or front tooth of the auxiliary feed dogelement 5, so that the tail T is automatically cut off. By referring toFig. 10, in conjunction with Fig. 9, the relationship of the indicatedparts during the thread severing operation, will be clearly understood.I

Operation From the foregoing description and explanation of a preferredembodiment of my invention, as applied to a Superlock sewing machine, itwill be apparent that the sewing thread is applied, as usual, in seamforming chain stitch formation, along an outer edge of the fabric workpiece acted on by the machine, as indicated in Fig. 5, wherein thefabric work piece and the seam forming stitch formation are respectivelyand schematically indicated by the letter F and the numeral 6.

During operation of the machine in usual manner, the fabric work piece Fmoves forwardly in the direction of the arrow shown in Fig. 5, until theseaming operation has been completed in the usual and well known mannerand until the rear edge of the fabric work piece passes beyond the fiatbottom surface of the rear section 7 of the foot shoe, or presser footelement E, substantially as shown in Figs. 9 and 10. At this point inthe operation of the machine, the foot shoe B will automatically drop,or move in downward direction, as usual, so that a certain portion ofthe sewing thread formation which trails the fabric work piece in theform of the seam tail T of reduced width in relation to the seam 6, willbe positioned between the bottom rear semi-circular cutting edgeestablished at the juncture of the vertical wall that defines theaperture A, and the sharp upper cutting edge of the front tooth of theauxiliary feed dog element 5, during the raised forward movement of saidtootl1, thereby automatically severing, cutting, or shearing off thesaid portion of the seam tail forming thread at this point,substantially as indicated in Figs. 9 and 10.

Modifications While I have shown the foot shoe E provided with acircular aperture E, in conjunction with certain other structural andfunctional features of my invention, to accomplish the indicated resultsand advantages, it will be readily understood by those skilled in thisart that the foot shoe bottom surface portion interrupting wallformation thus established to effect a cutting edge in crosswiseoverextending relation with the sewing thread, can be attained invarious other ways. For example, the aperture A may be otherwiseadjustably located in relation to the teeth of the auxiliary feed dogelement 5, or may have a different wall defining configuration, orshape, such as triangular, square, elliptical, etc., or the foot shoe Emay be provided with a substantially rectangular slot B as shown in Fig.11. Therefore, it is to be understood that the improvements, as hereinspecifically shown and described, can be changed and modified in variousways without departing from my invention, the scope of which is moreparticularly indicated and defined by the hereto appended claims.

I claim:

1. In a presser foot for sewing machines and the like having a needleopening therein, said presser foot having a fiat bottom surface portionalong which contactingly travels the work piece part to which a seam isto be applied when advancingly acted on by the teeth of a feed dogmember of the machine, an aperture formed in the presser foot rearwardlyof the needle opening and having a wall' portion presenting a cuttingedge on the bottom surface of the presser foot, said wall portionextending crosswise of the path of the seam thereunder, and being of awidth to contact one of the feed dog teeth in such manner that saidcutting edge and the said one of the feed dog teeth will becooperatively related to effect automatic severance of the thread tailof the seam rearwardly beyond the work piece.

2. In a presser foot for sewing machines and the like having a needleopening therein, said presser foot having a flat bottom surface portionalong which contactingly travels the work piece part to which a seam isto be applied when advancingly acted on by the teeth of a feed dogmember of the machine, a substantially circular aperture formed in thepresser foot rearwardly of the needle opening and having a wall portionpresenting a cutting edge on the bottom surface of the presser foot,said wall portion extending crosswise of the path of the seamthereunder, and being of a width to contact one of the feed dog teeth insuch manner that said cutting edge and the said one of the feed clogteeth will be cooperatively related to effect automatic severance of thethread tail of the seam rearwardly beyond the work piece.

3. In a presser foot for sewing machines and the like having a needleopening therein, said presser foot having a fiat bottom surface portionalong which contactingly travels the work piece part to which a seam isto be applied when advancingly acted on by the teeth of a feed dogmember of the machine; of a slot-forming aperture in the presser footrearwardly of the needle opening and having a wall portion presenting acutting edge on the bottom surface of the presser foot, said wallportion extending crosswise of the path of the seam thereunder, andbeing of a width to contact one of the feed dog teeth in such mannerthat said cutting edge and the said one of the feed dog teeth will becooperatively related to effect automatic severance of the thread tailof the seam rearwardly beyond the work piece.

4. In a presser foot for an edge seam applying sewing machine whichpresser foot has a needle opening therein, said presser foot having aflat bottom surface portion along which contactingly travels the workpiece to which a seam is to be applied when advancingly acted on by theteeth of a feed dog member of the machine, an aperture formed in thepresser foot rearwardly of the needle opening and having a wall portionpresenting a cutting edge on the bottom surface of the presser foot,said wall portion extending crosswise of the path of the seamthereunder, and being of a width to contact one of the feed dog teeth insuch manner that said cutting edge and the said one of the feed dogteeth will be cooperatively related toeifect automatic severance of thethread tail of the seam rearwardly beyond the work piece.

5. In a sewing machine having a thread applying needle, a stationaryneedle plate over which the work piece travels, and a work pieceadvancing feed dog member arranged to extend through an opening in saidneedle plate so as to engage the work piece part to which a seam is tobe applied; of a vertically movable presser foot having a needle openingtherein, said presser foot having a flat bottom surface portion adaptedto be placed in contacting relation on the work piece part to which aseam is to be applied when advancingly acted on by the teeth of saidfeed dog member; an aperture formed in said presser foot rearwardly ofthe needle opening and having a wall portion presenting a cutting edgeon the bottom surface of the presser foot, said wall portion extendingcrosswise of the path of the seam thereunder and being of a width tocontact a certain tooth of the feed dog member in such manner thatautomatic severance of the thread tail of the seam will be effectedbeyond the work piece by the cooperative action of said cutting edge andsaid one tooth of the feed dog member.

6. In an edge seam sewing machine having a thread applying needle, astationary needle plate provided with a chaining finger, and areciprocably operable work piece advancing feed dog member arranged toextend through an opening in said needle plate in spaced axially alignedrelation rearWardly of said chaining finger so that the feed dog memberwill engage the underside of the work piece part to which the thread isapplied in chain formation; of a vertically movable presser foot havinga needle opening therein, said presser foot having a flat bottom surfaceportion adapted to be placed in contacting relation on the top surfaceof the work piece part to which the thread is applied in chainformation, an aperture formed in said presser foot rearwardly of theneedle opening and having a wall portion presenting a cutting edge onthe bottom surface of the presser foot, said wall portion extendingcrosswise of the path of the seam thereunder and being of a width tocontact one of the teeth of the feed dog member in such manner thatautomatic severance of the thread tail of the seam will be effectedbeyond the work piece by cooperative action of said cutting edge and thesaid one tooth of the feed dog member.

References Cited in the file of this patent UNITED STATES PATENTS1,083,967 Weis et al. Jan. 13, 1914 1,118,589 Seymour Nov. 24, 19141,233,572 Heap July 17, 1917 1,547,930 Loeb July 28, 1925 1,663,488Berger Mar. 20, 1928 2,293,236 Anderson Aug. 18, 1942 2,605,729 EnosAug. 5, 1952 2,747,533 Enos May 29, 1956

